Lack of associations of the COMT Val158Met polymorphism with risk of endometrial and ovarian cancer: a pooled analysis of case-control studies

Investigation of Catechol-O-methyltransferase (COMT) gene Val158Met polymorphism in ovarian cancer

Objective:

Catechol-O-methyltransferase (COMT), the product of the COMT gene, detoxifies the carcinogenic catechol estrogens. The aim of the present study was to examine the relationship between COMT Val158Met polymorphism and the risk of ovarian cancer.

Material and Methods:

The study groups consist of 94 individuals as a patients group with ovarian cancer (n=47) and control group (n=47). The allele and genotype frequencies were determined according to Hardy-Weinberg equilibrium (HWE). The allele and genotype frequencies. determined according to HWE. Genetic analysis were performed by real-time-polymerase chain reaction instrument, and the statistical analysis were performed by SPSS program.

Results:

Although no significant relationship was obtained among groups (p=0.413) regarding COMT gene Val158Met polymorphism, the genotype frequencies for COMT Val158Met (rs4860) polymorphism in groups was homozygote wild type GG genotype 25.5%, heterozygote GA genotype 46.8%, homozygote mutant AA genotype 27.7%.

Conclusion:

This study is the first to investigate the relationship between ovarian cancer and the Val158Met polymorphism in the COMT gene in a Turkish population. No statistically significant relationship was identified among genotypes belonging to the patient and control groups although sample sizes were relatively small and the analysis should be repeated in a larger cohort.

Evaluation of COMT Gene rs4680 Polymorphism as a Risk Factor for Endometrial Cancer

Catechol-O-methyletransferase (COMT) enzyme is involved in the inactivation of catecholamine and catechol estrogens. Catechol estrogens have carcinogenic potential and DNA damaging ability. Several studies investigated COMT Val158Met polymorphism as risk factor for endometrial cancer but the results were inconclusive. Hence the objective of present study was to find out exact association between COMT gene Val158Met polymorphism and endometrial cancer by a meta-analysis. Pubmed, Google Scholar, Springer Link and Science Direct databases were searched for case-control articles which investigated COMT Val158Met polymorphism in endometrial cancer cases. All statistical analysis was performed using MetaAnalyst and Mix programs. The results of meta-analysis suggested that there were no association between COMT Val158Met polymorphism and endometrial cancer risk (allele contrast model-OR_{A vs. G} = 0.97, 95% CI = 0.86-1.10, p = 0.67; co-dominant model-OR_{AG vs. GG} = 0.91, 95% CI = 0.77-1.06, p = 0.23; homozygote model-OR_{AA vs. GG} = 1.01, 95% CI = 0.84-1.19, p = 0.29; dominant model-OR_{AA+AG vs. GG} = 0.93, 95% CI = 0.77-1.11, p = 0.43; recessive model-OR_{AA vs. AG+GG} = 1.02, 95% CI = 0.89-1.20, p = 0.62). Publication bias was absent. Subgroup analysis based on source of controls was also performed. In conclusion, results of present meta-analysis showed no association between COMT Val158Met polymorphism and susceptibility to endometrial cancer.

The Val158Met polymorphism in COMT gene and cancer risk: role of endogenous and exogenous catechols

Catechol-O-methyltransferase, COMT, is an important phase II enzyme catalyzing the transfer of a methyl-group from S-adenosylmethionine to a catechol-containing substrate molecule. A genetic variant Val158Met in the COMT gene leads to a several-fold decrease in the enzymatic activity giving rise to the accumulation of potentially carcinogenic endogenous catechol estrogens and their reactive intermediates and increasing thus the risk of tumorigenesis. However, numerous association studies between the COMT genotype and susceptibility to various malignancies have shown inconsistent and controversial findings indicating that additional gene-gene and gene-environment interactions might be crucial in modulating the physiological role of the COMT. In this review article, the important contribution of dietary catechol-containing flavonoids to modification of the relationships between the COMT genotype and cancer risk is discussed. Whereas, the diverse anticancer activities of common phytochemicals, such as green tea polyphenols, quercetin, fisetin or luteolin, can be markedly changed (both decreased or increased) by the COMT-mediated O-methylation of these exogenous substrates, flavonoids can also behave as potent inhibitors of the COMT enzyme slowing detoxification of endogenous catechol estrogens. Such a many-featured functioning of the COMT and its complex regulation by several different genetic and environmental factors, including plant-based food ingredients, emphasizes the necessity to further stratify the association studies between the COMT genotype and tumor risk by consumption of catechol-containing dietary flavonoids. Currently, it can be only speculated that some of the possible associations might be masked by the regular intake of specific food polyphenols, taking effect in certain communities or populations.

Association between the COMT Val158Met polymorphism and risk of cancer: evidence from 99 case-control studies

Catechol-O-methyltransferase (COMT) plays a central role in DNA repair and estrogen-induced carcinogenesis. Many recent epidemiologic studies have investigated the association between the COMT Val158Met polymorphism and cancer risk, but the results are inconclusive. In this study, we performed a meta-analysis to investigate the association between cancer susceptibility and COMT Val158Met in different genetic models. Overall, no significant associations were found between COMT Val158Met polymorphism and cancer risk (homozygote model: odds ratio [OR] =1.05, 95% confidence interval [CI] = [0.98, 1.13]; heterozygote model: OR =1.01, 95% CI = [0.98, 1.04]; dominant model: OR =1.02, 95% CI [0.97, 1.06], and recessive model: OR =1.03, 95% CI [0.97, 1.09]). In the subgroup analysis of cancer type, COMT Val158Met was significantly associated with increased risks of bladder cancer in recessive model, and esophageal cancer in homozygote model, heterozygote model, and dominant model. Subgroup analyses based on ethnicities, COMT Val158Met was significantly associated with increased risk of cancer in homozygote and recessive model among Asians. In addition, homozygote, recessive, and dominant models were significantly associated with increased cancer risk in the subgroup of allele-specific polymerase chain reaction genotyping. Significant associations were not observed when data were stratified by the source of the controls. In summary, this meta-analysis suggested that COMT Val158Met polymorphism might not be a risk factor for overall cancer risk, but it might be involved in cancer development at least in some ethnic groups (Asian) or some specific cancer types (bladder and esophageal cell cancer). Further evaluations of more preclinical and epidemiological studies are required.